Hydraulic transmission



Jan. 25, 1938. D. 5. DE LAVAUD 4 2,106,423

HYDRAULIC TRANSMISSION Filed July 3, 1934 4 Sheets-Shet 1 Fed.

Jan. 25, 1938.

D. 5. DE LAVAUD HYDRAULIC TRANSMI SS ION Filed July 5, 19:54 '4 Sheets-Sheet 2 Jan. 25, 1938. D. s. DE LAvAuD I HYDRAULIC'TRANSMISSION Filed July 3, 1954 4 Sheets-Sheet 4 IN V EN TOR.

B. S. De LavaucZ y- W zromwsys I Patented Jan. 25, 1938 UNlTED STATES PATENT OFFICE Application July 3, 1934, Serial No. 733,696 In France July 8, 1933 8 Claims.

, and-the pump, and have described various details of control and adjustment.

The apparatus is designed to operate as a hydraulic coupling between the pump and the turbine when the couple of the load is equal to that of the driving force. But it is practically impossible, without special provisions, to avoid a certain slip between-the pump and the turbine.

In Patent 2,034,429 I have described means for partly remedying this disadvantage by freeing the vane stator automatically or at will when the resisting couple imposed by the load on the turbine becomes equal to the couple imposed by the motor on the pump, so that the vane stator could becarried along in the same direction and at substantially the same speed as the turbine and the pump. But with this device there has still been a certain slip (ofthe orderv of 3 to 4 per cent) between the turbine and the pump 25 because the vane stator retards the passage of the. oil or-other fluid.

The present invention aims to remove this defeet by connecting the turbine and the pump automatically at a determined speed of rotation load is comparatively great andthe pump drives the turbine at a reduced speed. As the resistance diminishes the speed of" the turbine increases and also that of the pump, the relative speed of the turbine gradually approaching that of the pump. The connecting means are setto operate at the speed of the pump which is attained.

able devices, mechanical or otherwise; the connecting devices in turn being, controlled either by the speed of the turbine or (preferably) by 50 the speed of the pump or by both.

Preferably also theturbine shaft actuates a,

driven shaft by an intermediate gearing, which may be of the planetary type and which isadjustable to different positions-for actuating the 55 driven shaft forward at the same speed as the of .the pump. When the motor is started, the

(Cl. Bib- 54) driving shaft, forward at a reduced speed or backward, at will. l The invention includes also a certain number of particular features described in detail hereinafter. The accompanying drawings illustrate one example.

Fig. 1 is a longitudinal central section of the complete apparatus, partly in elevation. Fig. 2 is an elevation, partly in section, of the devices for connecting the pump and the turbine. Fig. 3 is a transverse section, theparts in different planes, through certain controls of the planetary transmission. Fig. 4 is a similar section of means for rigidly connecting the turbine shaft with the driven shaft. Fig. 5 is a'section approximately on the line V-'V of Figs. 3 and 4. Fig. 6 is an end view of the shaft and lever shown in Fig. 5. Fig. '7 is a transverse section of a pawl and ratchet between the vane stator and the frame,

of the apparatus. Fig. 8 is adetail in section on a larger scale of the mechanism forv braking one of the sets of planetary pinions. Fig. 9 is a front view of the said wedges, the shell of the turbine being removed or omitted and two of the wedges being shownpartly in sec- 5 tion for showing the engaging method of the springs which connect the said wedges together.

Fig. 10 is a section on line X--X of Fig. 9. Fig. 11 is a section on line- XI-Xl of Fig. 9. Fig. 12 is a section on line X[I--XII of Fig. 9. The hydraulic transmission mechanism illus-. trated by way of example comprises a pump! fixedly mounted on a shaft 2 driven by the motor, a turbine too-axial with the pump and a ring 4 carrying blades and serving as a vane stator when a centrifugal-pump is used or only as a directing ring when a helicoidal pump and turbine are used. The ring 4, turbine 3 and pump 'providea practically closed circuit for the fluid within the mechanism. The vane stator ring 4 is carried on a disc 4 which is mounted on a ball bearing carried by the hub of the turbine. Balanced pawls 82 (Figs. 1 and 7) are pivoted on pins 83 fixed on the disc 4. The free ends of the pawls are springpressed inward against a ratchet 84 carried by a hub 85 which is connected to sleeves 86. The sleeves are fixed at their other ends to the frame 36. Thus the vane stator is free to rotate with the turbine and the pump but is fixed against backward rotation. Y

The oil or other fluid within the casing is maintained under pressure by means of a gear pump, of which one pinion 81 is fixed on a sleeve 88 at-- tached to the shell of the pump I. The other The means for connecting together the pump and the turbine, of the type described or of vari-' ous other types, is illustrated particularly in Figs. 1 and 2. Onthe portion I of the shell of the pump there is mounted a plate I having its outer portion offset and carrying three guide blocks which enter grooves in three blocks 89 spaced at equal distances from each other and drawn inward by means of connecting springs 8| of determined tension. When the speed of rotation of the pump produces a centrifugal force sufficient tooffset the resistance of the springs, the blocks 80 are pressed against the shell of the turbine 3 and constitute a connection sufiiciently rigid to prevent slip between the pump and turbine.

When thespeed of the pump falls to the determined extent, the springs withdraw the blocks. The inward movement of the blocks is facilitated by inclining their grooves and the guide blocks 1 forward, that 'is in the direction of rotation as shown by the arrow, Fig. 2. The angle a between the radial direction and the direction of the movement of the blocks is made equal to the angle 'of friction. I

The connection between the pump and the turbine takes place at a determined rate of rotation of the pump. Preferably this rate is that at which the couple of the force exerted by the motor upon the pump is equal to the couple of the resistanceor load on the turbine. This corresistance and finally the speed reduction of the hydraulic mechanism ceases. Preferably also the chosen speed at which the connection is effected is that at which the motor has a maxi- 7 efiecting a rigid connection between the pump end of 'a turbine. shaft 5.

and the turbine at this speed, the motor will be operated at its highest efficiency over the principal part ,of the time that it is in use.

The principle of the invention may be applied to other types of hydraulic transmission and for other speeds and may, utilize other types of connectori (than as illustrated. The: connecting devices/[may be controlled mechanically and either by the speed of the pump or that of the turbine or by the relation between these two speeds or the relation between the driving and the resisting forces acting on the pump and the turbin respectively. The hydraulic transmission is preferably combined with mechanism between the turbine shaft and a driven shaft by which the latter can be rotated forward at the same speed as the turbine shaft or forward at a slower speed or backward. A planetary gearing is illustrated for this purpose in Fig. 1, with details in Figs. 3, 4, 5, 6, and 8. Y

The hub of the turbine 3 is keyed on the left Fixed to the other ended this shaft is the head I of a drum 9, l, P.

which are fixed in the heads 'I and I of the drum.

It will he understood that there are several groups of such pinions spaced angularly around the drum, as usual in planetary gearing. The diameter of the pinions is chosenin order to give the correct speed reduction forward and backward.

Where more than one speed reduction is desired, a larger number of pinions may be used in each group.

The pinion 8 engages a pinion l2 fixed on the left end of a driven shaft l3 which carries at its other enda coupling device H. The pinion 9 engages a pinion l5 fixed on a sleeve l6 which is concentric with thedriven shaft l3 and on which-is splined the hub I8 of a disc I], so that the disc can slide longitudinally on the sleeve IS. A pinion l2 carried by a sleeve 24 is engaged by the pinion I0.

The disc H has two annular tapering grooves in each face near its periphery. Any number of such grooves may be provided. The drum head 1 has corresponding annular ribs 2| facing the grooves at one side. At the opposite side issa disc 23 provided with corresponding ribs 22.

The hub of the disc 23 is angularly fixed on the sleeve 24 but is movable axially thereon.

Means are provided as follows for clamping the disc 23 against rotation, or for freeing it. On its periphery it has teeth 25 which have an axial sliding engagement with corresponding internal teeth in a ring 26 which may be clamped or released as hereinafter described.

The disc H has a peripheral fiange 21 which is also provided with external teeth 28 having an axially sliding engagement with internal teeth carried by a ring 29 which may be clamped fast or released. The disc 23 is pressed outward by springs 39 positioned between the discs 23 and I1. Similarly the disc IT is pressed outward by springs 3| bearing against the head 1 of the drum. When these springs are effective the ribs are withdrawn from the grooves sufii-. ciently to permit free rotation between the drum, the disc l1 and the disc 23. j I

The parts are pressed together and the ribr forced into the grooves of the disc I! by devices which force the disc 23 inward. On the hub 52 of the disc 23 is fixed the internal race of a ball bearing, of which the external race is carried by a ring 32. The ring 32 can be forced to the left against the pressure of the springs, thus forcing the ribs into the groove and by their friction connect the drum head I and the discs I! and 23 firmly together. This effects a fixed connection between the turbine shaft 5 and the driven shaft l3.

The angular movement of the ring 32 is produced by a cam 39 bearing on a roller 31 carried by a plate 38 fixed to the ring 32. The roller is held adjacent the cam by means of a spring 40 engaging a pin on the plate. 38. and connected Within the drum are three groups of pinions 9, 9, and Ill mounted freely-on shafts H at its opposite end to a cap 4| by means of a threaded'r'od l2 and nuts for regulating the v ratchet 61 having a number of teeth correspond- "bronze or the like.

ing to the number of high and low points of the cam, so that a rotation for a distance of one tooth turns the cam from a high point to a low point, or vice versa, and effects a corresponding maximum movement of the ring 32. The operation of the. shaft 44 is effected by a lever 48 mounted thereon and carrying a pawl 43 (Fig. 6) held in engagement with the ratchet by'a spring 50.. Thus alternate oscillations of the lever 68,

by means of a pedal or the like, operate the shaft 46 through a determined distance, the -movement in the direction of the arrow alone operating the shaft.

Each movement of the lever 48 therefore locks the disc with the drum 6 and'the disc23, or releases these three parts from one another.

The rings 26 and 29 are preferably made of They are fixed against angular movement with respect to the discs l1 and 23. When these rings are clamped against movement the corresponding discs are also heldfast.

The outer faces of the toothed rings bear against annular ribs 53 and 54 fixed to the frame, integrally or by attachment thereto.

On the inner sides of the toothed rings are brake rings 55 and '51 adapted to slide axially and a fixed ring 56 in the center. The central ring serves as an abutment for devices which press the brake ring 55 outward to clamp the toothed ring 29 and thus hold the disc l'i stationary, orto press the brake; ring 51 outward against the toothed ring 26 and thus holdthe disc 23 stationary.

The center ring 56 is fixed in the casing by means of a screw 56*, Fig. 3, and is lodged in a groove 69, Fig. 1, in the casing which prevents axial movement. The brake rings 55 and l can be turned and also shifted laterally. The central ring carries on each lateral face inclined recesses 58 approximately opposite the similar recesses 59 in the brake ring (Fig. 8). Between the two recesses is a ball 66 which when the 1 brake ring is turned in one direction rides on the inclines and forces the brake ring firmly againstthe toothed ring in question; and which, when the brake ring-is moved in the opposite direction, lies in the deeper 'parts of the grooves and removes the clamping action.

The rotation of the clamping rings is obtained by means of cams 6| and 62 (Figs. 3 and 5).

They are splined on the shaft 44 and are set at a right angleto each other. Fig. 3 is in two planes of section illustrating the two clamping rings 55 and 51. Each of these has a projection 64 lying between a rod 63 forced in one direction by the cam and arpd 65 forced in the opposite direction by a 66 held by a cap 61. The springs turn-1 the rings to the clamping position. The cams turn them to the released position.

Fig. 3 shows them both-released (or they may both be clamped) at one time- The two cams BI and 62 are in one piece which is splined on the shaft 44 to permit axial displacement. The profile of the cams 6| and 62 corresponds to, that of the cam 39 in having the same number of high points and low points oppositely placed.

The two cams 6| and 62 can be shifted to an inoperative position (leaving the-clamping rings backward drive.

in clamping position to hold the toothed rings stationary).by means of a finger 68 lying in a circumferential groove 69* of the cam block and mounted on a crank vlll (Fig. 3) on a short shaft II to which is keyed a grooved pulley 12 whose rotation is effected by suitable means, such as a in a part 11 which serves as a bearing for the shaft H and which is fastened to the frame 36 by a screw 18 or the like. 7

The cams 6| and 62 can take three positions; the first corresponding to a forward reduced speed, the second in which both cams are out of action and the discs l1 and 23 are firmly clamped to the drum and the third corresponding to the The relative position of the cams 6| and 62 to that of the cam 33 is such that when-the latter is at a low point (corresponding to a direct coupling of the turbine and thedriven shaft) the two cams 6| and 62 are at their dead point.

The relation and function of various parts will now be explained in detail for a clearer understanding of the same.

- These wedges or blocks 30 are identical and relatively displaced at an angle of 120. Each of these wedges 80 is designed circumferentially so astohave a thickness which decreases in such manner that the lateral faces of each of the said blocks form a wedge adapted to engage, when these wedges are displaced outwardly, between the. faces situated opposite and conformably to the shells of the pump and of the turb7ne 3 for rigidifying these two shells as hereinafter explained.

r The blocks 80 are arranged against the facev l of the shell of the pump and are held against this spring and adapted to enter recesses formed face by means of a check secured by any suitable'means to the shell I of "the pump. These blocks 80 are secured to the said cheek and guided thereon through the medium of grooves formed in the said blocks and in which are ad- -justed projections or guides secured by any suitable means such as rivets I to the cheek which is rigidly secured to the shell of the pump.-

The blocks 80 are connected together by antag onistic springs 8| suitably calibrated so that the outward displacement of the blocks 83 under the influence of the centrifugal force created by therotation of the.shell of the-pump on which are mounted the said blocks is effected for a definite speed of rotation of the said pump and which may be for example that speed for which the driving couple on the pump is equal to the resist ing couple on the turbine.

According to the invention and for reasons. winch. will be hereinafter explained, the grooves formed in the blocks 86 as well as the projections or guides rigid with the cheek l are in clined in the corresponding. radial direction and according to the directionof rotation at an angle equal in principle to the angle of friction a. The centrifugal displacement of the blocks 86 is thereby efiected according to this direction inclined at the angle a to the corresponding radius extending in principle through the center of gravity of the block under consideration.

The operation of the rigidifying means is as follows:

It is assumed that the said wedges are mounted on the shell of the pump as is the case.

rigidify the shells of the pump and turbine.

There is then a rigid connection between the pump and the turbine without which there would be a slip between these two members, in other words there is a rigid drive between them. Assuming there exists a slight slip between the turbine and the pump, the turbine being the resisting member, this slip is only produced owing to the fact that the turbine tends to rotate less quickly than the pump. In other words, there exists a relative rotation between the pump and the turbine and this relative rotation takes place in the direction of rotation common to the pump and the turbine, that is to say, in the direction indicated by the arrow f in- Fig. 9 of the accompanying drawings. It is obvious from this figure that this slip produces on the wedge 80 a series of forces whose resultant R applied to the center of the said wedge 80 is directed tangentially and in the direction of the arrow J. This force R is adapted to be separated into two forces, one force R being directed according 'to the direction of displacement of the wedge 80 and the other R2 directed perpendicularly to the said direction.

The component R1 tends to displace the wedge externally, that is to say, to penetrate this wedge between the rubbing surfaces of the pump and the turbine after the manner of a wedge in antagonism tovthe force of retraction F exerted by the resistance on' the turbine increases, it is obvious that in this case it is the turbine which reduces the speed of the unit or, in other words, the turbine tends to rotate less quickly than the pump. It is assumed that the speed of the unit (pump and turbine) decreases slightly below the predetermined speed or critical speed for which there is no rigid connection between the two members; an examination will now be made to ascertain what is produced on the return of the jamming wedges under the action of the springs.

An examination will be made of only one of the wedges and it will be assumed that the various forces under consideration are applied at a point A placed at the center'of gravity of the said wedge. Owing to the rotation at a speed lower than the critical speed, it is obvious that the wedge is subjected to a centrifugal force of reis opposed to the displacement-itis obvious that the actual force T exerted on the wedge forms an angle a with the force T, the angle a being equal to the angle of friction. It is therefore obvious that the wedge is subjected to two forces F and F: one force F is radial and the other force T' perpendicular to the-direction of dis-v placement of the wedge 80 under consideration since according to the invention, this direction is inclined at an angle or to the corresponding radius.

Consequently, there does not exist a component directed according to the direction of displacement and opposing the said displacement which can then be produced under the action of a very weak force, that is to say, with very weak antagonistic springs 8|.

The functions of the several parts having been explained, a brief statement will serve to explain the operation of the whole.

When the pump I is driven by the motor, the fluid in the hydraulic circuit is displaced in the direction of the arrow 94 and drives the turbine. o

in the same direction as the turbine and pump.

As hereinabove explained the blocks 80 are forced out by centrifugal force to connect the turbine and the pump and to prevent any slip between them. If the speed of the turbine diminishes, so does that of the pump rigidly connected to it, the connecting blocks are withdrawn by their springs, and the vane stator is stopped by the pawls engaging the ratchet.

To secure a direct drive of the shaft l3 by the turbine, the cams 6| and 62 are first put out of action through the pulley 12 and the crank pin 68. The drum and the discs I! and 23 are connected by turning the cam 39 to the proper point by means of the arm 48.

To advance at reduced speed, the cams BI and 62 are shifted on their shaft to bring them into operative positions. The lever 48. is then operated; 1) to release the drum and the discs I1 and 23 and (2) to turn the cams so as to clamp by cam 62 the disc I! which engages. and holds fast the pinion I5 corresponding to a backward movement.

For the backward drive at reduced speed the lever 48 is first actuated. Then the cams 6| and 62 are turned to the position corresponding to the backward movement and then the lever I8 is operated again.

The invention is not limited to the particular embodiments illustrated and described. Various modifications may be made in the several parts and in the arrangement thereof without departing from the invention as defined in the following claims.

What I claim is:

1. Improvements in hydraulic transmission mechanism comprising a driving shaft, a driven shaft, a rigid member including a pump keyed on said driving shaft, a rigid member including a turbine keyed on said driven shaft, a vane stator between the turbine and the pump, means actuated by the centrifugal forceat a certain speed of one of said shafts to rigidly connect said driving and driven shafts, said means wedging between rigid members on the driving'and driven shafts respectively.

2. The device as claimed in claim 1, in which there are means for preventing the wedging means from acting in one direction of rotation.

3; Improvements in hydraulic transmission mechanism comprising a driving shaft, a driven shaft, a rigid member including a pump keyed on said driving shaft, a rigid member including a turbine keyed on said driven shaft, a vane stator between the turbine and the pump, means actuated by the centrifugal force at a certain speed of one of said shafts to rigidily connect said driving and driven shafts, said means wedging between the shell of the pump andthe shell of the turbine.

4. Improvements in hydraulic transmission mechanism comprising a driving shaft, a driven shaft, a rigid member including a pump keyed on a said driving shaft, a rigid member including a turbine keyed on said driven shaft, a vane stator between the turbine and the pump, means actu-' ated by the centrifugal force at a certain speed of one of said shafts to rigidly connect said driving and driven shafts, said means wedging between rigid members on the driving and driven shafts respectively, and comprising wedging blocks carried by one of said members, yielding means suitably calibrated opposing the centrifugal force whereby the said blocks engage with the other member under the action of the centrifugal force created by a predetermined speed shaft, a rigid member including a pump keyed on said driving shaft, a rigid member including a turbinekeyed on said driven shaft, a vane stator 5 of rotation of the member carrying the-said blocks.

between the turbine and the pump, means actuated by the centrifugal force at a certain speed of one of said shafts to rigidly connect said drivradial direction, said angle being substantially equal to the angle of friction between the wedging blocks and the rigid members of the pump and the turbine.

7. The device as claimed in claim 4, in which said yielding means comprise springs connecting the block in pairs.

8.' The device as claimed in claim 6, in which said yielding means comprise springs connecting v the blocks in pairs.

- DIMITRI SENSAUD n2: LAVAUD. 

